Novel ortho-alkoxy-substituted phosphorus ylides and their stereoselectivity in Wittig reactions

The stereochem. of the reactions between tris(2-methoxymethoxyphenyl)phosphonioethanide, -butanide (I) and -phenylmethanide and a variety of aldehydes was investigated. Ylides having a b-unbranched aliph. sidechain, such as I, and satd. straight-chain aldehydes give olefins with unprecedented cis-selectivity (cis/trans 200:1). [on SciFinder (R)]